1. Field
The present invention relates generally to a compartment pressure relief valves and, in particular, to compartment pressure relief that operates irrespective of gravity.
2. Description of the Related Art
Many current automobile designs incorporate compartment pressure relief valves that allow air pressure, built up in the vehicle compartment through running of an air conditioner or shutting a door, to escape the compartment to ensure a comfortable environment. Many designs are flap-type valves, for example, U.S. Pats. Nos. 4,972,765 to Dixon, 5,355,910 to Gies et al, 6,210,266 to Barton, and 6,458,027 to Stiehl and U.S. Pat. App. Pub No. 2003/0017799 (Hayashi, et al). A common feature of these valve designs is that they rely upon the force of gravity to close the valve. Therefore, the valve must be oriented in the vehicle structure so that it may close properly with gravity, i.e., they must be upright and mounted within a vertical structure of the compartment. This has some disadvantages.
One disadvantage is that the provision for pressure relief in vehicle design is often an after-thought. The pressure relief valve must be specially designed for the space provided for it, which is typically the engine compartment firewall, the rear wall or a door, and machinery must be specially tooled to fabricate the valve. This leads to increased expense and, perhaps increased time from design to market. Furthermore, vehicles parked on steep inclines may allow the gravity-dependent valves to open when not desired.
There have been attempts to create gravity-independent valves which may be placed within any vehicle compartment wall without consideration of orientation. Some of these designs spring-load the flap in the closed position, but this increases the parts required to make the valve and increases the odds of mechanical failure.
One highly-prized goal in many vehicle designs is noise reduction. The above designs do not contribute to this goal as they tend to suffer from undesirable noise levels during use as a result of the flap re-engaging with the valve seat when closing.
For the foregoing reasons, there is a need for a low-cost vehicle compartment pressure relief valve that can be mounted in any orientation in the vehicle structure and that meets or exceeds current noise reduction design levels.